The present disclosure relates to a solid-state imaging device and a driving method thereof, and an electronic apparatus, and in particular, to a solid-state imaging device and a driving method thereof, and an electronic apparatus, capable of improving characteristics of pixels.
In the related art, in electronic apparatuses with imaging functions, such as digital still cameras and digital video cameras, solid-state imaging devices such as, a Charge Coupled Device (CCD) and a Complementary Metal Oxide Semiconductor (CMOS) image sensor are used. The solid-state imaging devices include a pixel in which a photodiode (PD) performing photoelectric conversion and a plurality of transistors are combined and an image is formed based on pixel signals which are output from a plurality of the pixels which are arranged in a plane manner.
For example, in the solid-state imaging device, charges accumulated in the PD are transferred to a Floating Diffusion (FD) unit having a predetermined capacity which is provided in a connection portion between the PD and a gate electrode of an amplifying transistor. Then, signals corresponding to a level of the charges stored in the FD unit are read from the pixel and AD-converted by an Analog Digital (AD) conversion circuit having a comparator so as to output the AD-converted signals.
In recent years, the solid-state imaging devices tend to have many pixels. Thus, when a pixel miniaturization is intended without changing the chip size, there is a problem that the light incident characteristics deteriorate and color mixing occurs between pixels.
For example, Japanese Unexamined Patent Application Publication No. 2010-169911 discloses a solid-state imaging device which performs an element separation optically and electrically by embedding an inter-pixel element separation film and a pixel light shielding film on a side on which light of a PD is incident, in order to reduce the color mixing between pixels. Further, Japanese Unexamined Patent Application Publication No. 2011-40531 discloses a solid-state imaging device that suppresses generation of a dark current by employing a fixed charge film.
Further, it has been known that the color mixing between pixels can be significantly reduced by employing an embedding technology in the solid-state imaging device.
Furthermore, Japanese Unexamined Patent Application Publication No. 2004-306144 discloses a solid-state imaging device that assists a charge transfer, for example, by applying a voltage to a poly-silicon embedded in a trench portion other than a drive signal of a normal pixel. Further, it is possible to intend to suppress the dark current, to improve a saturation charge amount, and to realize a low voltage drive, by applying a voltage to the trench portion.
In addition, Japanese Unexamined Patent Application Publication No. 2007-25807 discloses a solid-state imaging device capable of intending to suppress the dark current and of improving the saturation charge amount, by providing electrodes in an upper part and a lower part of the PD so as to apply a suitable voltage.